1. Field of the Invention
The present invention relates to disk devices capable of recording and/or playing back disks such as compact disks (CDs) or digital versatile disks (DVDs), and in particular, relates to disk devices of a changer type capable of playing back a disk selected from a plurality of accommodated disks.
2. Description of the Related Art
A car-mounted disk device of a changer type includes a disk tray or a stock section into which a plurality of disks are loaded from a loading slot so as to be stacked in the axial direction. When a desired disk is selected from the disks in the disk tray, the disk is rotated by a driving unit, and the data on the disk is read out by an optical head.
Japanese Unexamined Patent Application Publication No. 11-283318 discloses a disk device of a changer type that detects the presence of disks in a changer by photosensors whose number equals that of acceptable disks. Accordingly, the presence of the disks accommodated in the changer can be immediately detected.
Japanese Unexamined Patent Application Publication No. 2002-32950 discloses a disk device of a disk selection type. In this disk device, when a driving unit is transferred to a retracted position, a rotational member is disposed at a position in a retraction space, and an optical head is disposed at another position in the retraction space separately. Thus, the driving unit can be accommodated in a casing with a limited capacity.
The disk device of the changer type has a so-called disk-check function for checking the content of the disks accommodated therein at power-on. When the disk-check function is performed, the table of contents (TOC) of all the accommodated disks is read out and shown on a display as a list. For example, a list of names of albums and artists is shown for music CDs such that users can select a disk to be played back with reference to the information.
However, when performing the disk-check function, the known technology has the following problems: The mounting space for the disk device of the changer type, in particular, an in-dash disk device with 1-DIN size, is limited; and accordingly, the space inside the casing is also limited. Therefore, the disk device transfers the disk tray accommodating the plurality of disks in the stacking direction of the disks, and horizontally transfers the driving unit between a playback position where the driving unit overlaps with the disks in the disk-stacking direction and the retracted position where the driving unit does not overlap with the disks. When a desired disk is selected, the height of the disk tray in the disk-stacking direction is adjusted, and then the driving unit is transferred to the playback position. Thus, the selected disk is read.
The disk checks in such a disk device are performed along an operational flow shown in FIG. 11. When the disk device is powered on (Step S301), the driving unit is transferred to the retracted position (Step S302). Then, the height of the disk tray is changed (Step S303), and a first disk (for example, the lowest disk) is selected (Step S304). Next, the driving unit is transferred to the playback position (Step S305), and the TOC of the disk is read by the driving unit (Step S306). The driving unit is then transferred to the retracted position (Step S307). Subsequently, the operations from Step S302 to Step S306 are repeated by a number of times equal to the number of acceptable disks in the disk tray (Step S308).
In this manner, the TOC of all the disks accommodated in the disk tray is read. When the disk tray accommodates the disks up to the capacity, the above-described steps are all necessary. However, even when the disk tray accommodates disks less than the capacity and no disk is accommodated in the selected position of the disk tray, the driving unit is transferred from the retracted position to the playback position. These operations are unnecessary and consequently waste time for the disk checks more than necessary.